Hi Im working on ford mondeo mk4 and so far discovered that there are multiple communication faults. Checked the resistance, voltage… On osciloscope can high and can low are good but occasionally the network spikes and also the relay of glowplugs starts clicking for few seconds. This happens at random time but also when i open/close doors. When i turn the ignition on the relay is also clicking and also i can hear air intake actuator goes on and off. The thing is… I think that these things are only symptoms, tried many things but I dont know where else to go. What could produce these faults. The BCM and ECM were replaced and nothing has changed. Do you have any suggestions?
Are you saying that on your scope screen can hi is a clean square wave between 2.5 and 5 volts and can lo is a clean square wave between
2.5 and 0 volts? And then network comm spikes or becomes erratic? If so that suggests a wiring issue, perhaps water intrusion or an intermittent short like wiring has been rubbing on something.
Your car is not sold in the US so most here would not be familiar with it. But first yoy need to identify which network is affected, as there are more than one in the car. Do your fault codes indicate which?
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A faulty battery could cause those symptoms. It might measure the correct voltage w/no load, but might go too low during cranking and confusing the computers. Suggest to start with battery/alternator functional test.
Glow plugs? Is this a diesels?
When the relay starts to click(at random time, or when i close or open door) this is what it looks like on osciloscope. After spike comes few seconds dead line at 2,5V. The images are on different site, could not upload them here.
Battery is new
Yes it is diesel
But why would it shorted only when the door is opened/closed. Or every few seconds. Could it be module itself? Or some other thing that sends false information to module and then module is doing wrong things. The are 3 network. Problem occurs in modules that are in can netwrok high speed. I tried to disconnect i think all the modules on the network but so far problem is still there.
I think Ford Mondeo was called “Ford Contour” in the USA . . . but we didn’t have the diesel engine option
+1
That model was originally intended to be Ford’s “world car”, but they wound-up making a LOT of changes that made the European version very different from the US version.
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A somewhat common failure mode is when the wires going between the chassis and door fail from repeated bending/flexing. This can result in broken insulation and shorting between the wires and/or ground. I don’t know your particular car but some have door modules that are on the CAN bus and communicate with the BCM. On some cars, when you open the door, the BCM wakes up. So it could be the door wiring or just the act of the BCM waking up and trying to communicate with other modules on the bus. Do you have a tool that can read CAN bus errors? Probably some clues there…
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At this point I think you will need a detailed wiring diagram, service manual indicating which modules are on which CAN and where they are, and a professional level scan tool that can perform a network test.
Or, if you are certain that opening and closing the door sets the faults, see Twin Turbo’s reply above.
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Looks like you have a module causing a problem on the bus. This disrupts the entire bus so other modules can’t communicate. Maybe a grounding fault on one of the modules.
Have you measured the Voltage between the engine and the vehicle chassis? Opening a door turns on lights, and turning on the cabin fan increases the ground potential of the chassis like opening the door does. That is if there is a chassis to battery weak ground.
Fords since the last 15 at least have a high speed and low speed CAN bus. The low speed is for climate control, radio, and all of that non essential stuff.